Inflatable boats have known a very substantial growth because of the advantages which they present in respect of their buoyancy and their unsinkability in comparison with rigid hull boats. They are divided at present into two principal types according to the design of the hull
Boats with a flexible hull, corresponding to the original type, comprising a hull which is constituted by a flexible canvas extending under the rigid bottom of the boat and a keel is interposed between the rigid bottom and the canvas in order to stretch it and give it, in transverse section, approximately the shape of a widely open V. The keel can be ordinary and, originally rigid, it is today often constituted by a fender, which is usually pneumatically inflatable. The main advantage of this type of boat lies in the small space which it occupies when it is dismantled, deflated and folded, which makes it easy to stow and transport. On the other hand, the lack of rigidity of its hull and especially the too open V shape of this hull give it mediocre characteristics of seaworthiness, particularly for course holding.
Boats with a rigid hull comprise a hull generally of synthetic material (reinforced composite material) whose peripheral edge is fixed, at the front and laterally, to an inflatable buoyancy fender. These boats retain the characteiristics of buoyancy and unsinkability of inflatable boats and in addition their rigid pronounced V shaped hull gives them good characteristics of seaworthiness, in particular for course holding. However, their major disadvantage lies in the rigid composition and casting of the hull in one piece (often manufactured all in one piece with the transom), which then forms a relatively heavy and bulky piece: the dismantling and deflation of the boat does not offer any substantial advantage for being stowed end transported, and these boats must usually be transported on specialised trailers. This significant disadvantage has limited the growth of boats with a rigid hull and has restricted this layout mainly to top-of-the-range boats.